[Correlation between reduction of distortion product otoacoustic emission and percentage of outer hair cell missing in chinchillas].

To explore the quantitative relationship between the reduction of distortion product otoacoustic emission (DPOAE) and the percentage of outer hair cell loss. Coadministration of cisplatin (0.2 mg/kg) and ethacrynic acid (40 mg/kg) were used to establish a cochlear lesion model in chinchillas. DPOAE was measured before and 1 week, 2 weeks, and 3 weeks later respectively after cisplatin and ethacrynic acid treatment. Animals were terminated 3 weeks after the treatment. Cochlear surface preparations were performed, and the cochlear hair cells were counted through entire length of the cochlea. The correlation between DPOAE reduction and outer hair cell missing was analyzed using Pearson correlation analysis. Cisplatin and ethacrynic acid treatment induced cochlear hair cell lesion that the outer hair cell loss in the cochlea developed in a stereotypic pattern; damage began in the base of the cochlea and progressed towards the apex. Reduction of DPOAE was relatively consistent with outer hair cells loss. On the average, 1% outer hair cells loss may result in 0.24 dB reduction in DPOAE levels. Pearson analysis showed a positive correlation between the reduction in DPOAE and missing of outer hair cells (r = 0.796, P < 0.05). It may be helpful to evaluate missing percentage of outer hair cells from reduction in DPOAE levels.